Aude-Marie Grapperon

Motor unit number index (MUNIX): Is it relevant in chronic inflammatory demyelinating polyradiculoneuropathy (CIDP)?

OBJECTIVE To determine the test-retest reliability of motor unit number index (MUNIX) technique and to explore if the MUNIX sumscore could be related with disability in chronic inflammatory demyelinating polyradiculoneuropathy (CIDP). METHODS The MUNIX technique was unilaterally assessed in the abductor digiti mini (ADM), the abductor pollicis brevi (APB) and the tibialis anterior (TA) muscles two different times by two blinded examiners. The MUNIX sumscore was calculated by adding the results of the ADM, APB and TA muscles. RESULTS 14 CIDP patients were enrolled. The intraclass correlation coefficient (ICC) was great for inter and intra variability for ADM muscles (0.8 and 0.81), TA muscles (0.86 and 0.89) and MUNIX sumscore (0.76 and 0.83). The MUNIX sumscores from the first and second evaluations were strongly correlated (r=0.83, p<0.001). The MUNIX sumscore was significantly correlated with MRC testing (r=0.71, p<0.01), overall neuropathy limitation scale (ONLS) (r=-0.70, p<0.001), rasch-built overall disability scale (R-ODS) (r=0.71, p<0.001). CONCLUSIONS The MUNIX technique has a good reproducibility and the MUNIX sumscore is related to the disability. SIGNIFICANCE The MUNIX technique estimates the axonal loss and the number of functional motor units. The MUNIX sumscore may be a good instrument to evaluate the CIDP patients during their follow-up.

Association between structural and functional corticospinal involvement in amyotrophic lateral sclerosis assessed by diffusion tensor MRI and triple stimulation technique

Introduction: We investigated the functional and structural integrity of the corticospinal tract (CST) using diffusion tensor imaging (DTI) and the triple stimulation technique (TST) in patients with amyotrophic lateral sclerosis (ALS). Methods: Fourteen patients with ALS, 13 healthy controls (HCs), and 6 patients with lower motor neuron (LMN) syndrome underwent DTI and TST. Results: The mean diffusivity was higher in ALS patients than HCs (P < 0.01). The TST ratio was lower in ALS patients compared with HCs (P < 0.001) and in LMN patients compared with HCs (P < 0.05). The increase in the mean diffusivity was correlated with the decrease in the TST ratio (P < 0.01). Conclusions: Significant correlations exist between the DTI and TST results, indicating both structural and functional involvement of the CST in patients with ALS. Muscle Nerve 49:551–557, 2014

Region-specific impairment of the cervical spinal cord (SC) in amyotrophic lateral sclerosis: A preliminary study using SC templates and quantitative MRI (diffusion tensor imaging/inhomogeneous magnetization transfer)

In this preliminary study, our objective was to investigate the potential of high‐resolution anatomical imaging, diffusion tensor imaging (DTI) and conventional/inhomogeneous magnetization transfer imaging [magnetization transfer (MT)/inhomogeneous magnetization transfer (ihMT)] at 3 T, analyzed with template‐extracted regions of interest, to measure the atrophy and structural changes of white (WM) and gray (GM) matter spinal cord (SC) occurring in patients with amyotrophic lateral sclerosis (ALS). Ten patients with ALS and 20 age‐matched healthy controls were recruited. SC GM and WM areas were automatically segmented using dedicated templates. Atrophy indices were evaluated from T2*‐weighted images at each vertebral level from cervical C1 to C6. DTI and ihMT metrics were quantified within the corticospinal tract (CST), posterior sensory tract (PST) and anterior GM (aGM) horns at the C2 and C5 levels. Clinical disabilities of patients with ALS were evaluated using the Revised ALS Functional Rating Scale, upper motor neuron (UMN) and Medical Research Council scorings, and correlated with MR metrics. Compared with healthy controls, GM and WM atrophy was observed in patients with ALS, especially at lower cervical levels, where a strong correlation was also observed between GM atrophy and the UMN score (R = −0.75, p = 0.05 at C6). Interestingly, a significant decrease in ihMT ratio was found in all regions of interest (p < 0.0008), fractional anisotropy (FA) and MT ratios decreased significantly in CST, especially at C5 (p < 0.005), and λ// (axial diffusivity) decreased significantly in CST (p = 0.0004) and PST (p = 0.003) at C2. Strong correlations between MRI metrics and clinical scores were also found (0.47 < |R| < 0.87, p < 0.05). Altogether, these preliminary results suggest that high‐resolution anatomical imaging and ihMT imaging, in addition to DTI, are valuable for the characterization of SC tissue impairment in ALS. In this study, in addition to an important SC WM demyelination, we also observed, for the first time in ALS, impairments of cervical aGM.

Global motor unit number index sum score for assessing the loss of lower motor neurons in amyotrophic lateral sclerosis

As we move toward treatments for amyotrophic lateral sclerosis (ALS), biomarkers are needed that provide clinically meaningful measures. In this article, the authors demonstrate that a global motor unit number index (MUNIX) sum score, reflecting the aggregate MUNIX of several muscles, is correlated with clinical impairment, and thus is potentially such a biomarker. In an accompanying editorial, ALS expert Dr. Clifford Gooch discusses the use of MUNIX and of motor unit number estimation (MUNE) as biomarkers in ALS.We propose a motor unit number index (MUNIX) global sum score in amyotrophic lateral sclerosis (ALS) to estimate the loss of functional motor units.

Determinants of Health‐Related Quality of life in anti‐MAG neuropathy: a cross‐sectional multicentre European study

Our objective was to assess determinants of quality of life (QoL) in anti‐myelin associated glycoprotein antibody (MAG) neuropathy. The SF‐36 questionnaire was assessed in 55 patients, from Marseille, Angers (France) and Birmingham (UK). Routine clinical evaluations included Medical Research Council (MRC) sum score, inflammatory neuropathy cause and treatment (INCAT) sensory score, inflammatory Rasch‐built overall disability score (I‐RODS), ataxia score, Jamar grip dynamometry, timed 10‐m walk, neuropathic pain symptom inventory (NPSI) score, and fatigue severity score (FSS). Physical component summary (PCS) and mental component summary (MCS) of the SF36 questionnaire were significantly lower than in reported normal subjects of both countries (p < 0.001). All SF‐36 domains correlated with I‐RODS, except MCS for which significance was, however, approached (p = 0.056). PCS correlated with MRC sum score, ataxia score, timed 10‐m walk, tremor, Jamar grip dynamometry, NPSI pain score, FSS and level of social support. MCS correlated exclusively with FSS and level of social support. In multivariate regression, PCS was associated independently with I‐RODS (p < 0.001) and NPSI pain score (p = 0.011), whereas MCS was associated independently with FSS (p = 0.022). QoL is accurately predicted in anti‐MAG neuropathy by the I‐RODS and FSS, lending support to their use in clinical and research settings. Effective measures to improve QoL should include tremor and neuropathic pain treatment, fatigue management, and improved social support.

Proximal conduction block in the pharyngeal–cervical–brachial variant of guillain–barrÉ syndrome

Introduction: Conduction block (CB) has been included in the Rajabally criteria for axonal Guillain–Barré syndrome (GBS). Because the nerve roots may be affected early in GBS, detection of proximal CB by the triple stimulation technique (TST) can be useful. Methods: We describe TST findings in 2 patients who presented with the pharyngeal–cervical–brachial (PCB) variant of axonal GBS. Results: In the first patient, although conventional nerve conduction studies (NCS) did not fit electrodiagnostic criteria for axonal GBS, the TST detected proximal CB in the median and ulnar nerves. In the second patient, NCS fulfilled criteria for axonal GBS, and the TST detected proximal CB in the median nerve. After plasmapheresis, NCS and TST findings were normalized, suggesting reversible conduction failure rather than demyelinating CB. Conclusion: The TST may be useful for diagnosis of PCB when NCS remain inconclusive. The technique provides additional clues for classifying PCB into the acute nodo‐paranodopathies. Muscle Nerve 52: 1102–1106, 2015

Prevalence, correlates and impact of pain and cramps in anti-MAG neuropathy: a multicentre European study

The frequency of pain and cramps is uncertain in anti‐myelin associated glycoprotein antibody (anti‐MAG) neuropathy. Whether these symptoms may affect function/quality of life is unknown.

Monitoring the short-term effect of intravenous immunoglobulins in multifocal motor neuropathy using motor unit number index

OBJECTIVE To determine whether motor unit number index (MUNIX) is pertinent to monitor the effect of intravenous immunoglobulins (IVIg) in multifocal motor neuropathy (MMN). METHODS MUNIX was assessed longitudinally in 7 MMN patients and 17 healthy controls in the abductor pollicis brevis (APB) and abductor digiti minimi (ADM) muscles. A MUNIX sum-score and a compound muscle action potential (CMAP) sum-score were calculated by summing up the scores of APB and ADM. MMN patients were evaluated on the first day of IVIg infusion, 5 MMN patients were evaluated 22days after IVIg infusion, and 3 MMN patients were evaluated 1month after two IVIg infusions. RESULTS Intraclass correlation coefficient of the MUNIX sum-score in healthy controls was 0.85, showing good test-retest reproducibility. MUNIX and CMAP sum-scores were lower in MMN patients than in healthy controls (p<0.01 and 0.02, respectively). MUNIX sum-score improved in three of the five patients 22days after IVIg infusion and in two of the three patients 1month after 2 IVIg infusions, whereas CMAP sum-score improved in only one patient in both evaluations. CONCLUSIONS In this preliminary study, MUNIX seems to be a reliable and sensitive tool to monitor the short-term efficiency of IVIg in MMN. SIGNIFICANCE MUNIX can help monitor IVIg treatment in MMN.

Motor-evoked potential gain is a helpful test for the detection of corticospinal tract dysfunction in amyotrophic lateral sclerosis.

OBJECTIVE The detection of upper motor neuron (UMN) dysfunction is necessary for the diagnosis of amyotrophic lateral sclerosis (ALS). However, signs of UMN dysfunction may be difficult to establish. This study aimed to determine whether motor-evoked potential (MEP) gain (MEP area/background electromyographic activity) represents an efficient alternative to assess UMN dysfunction. METHODS MEP area, MEP/compound muscle action potential (CMAP) area ratio, and MEP gain were tested at different force levels in healthy control subjects and ALS patients. Receiver operating characteristic (ROC) curve analyses was used to determine the diagnostic utility of MEP gain and compare it to alternative techniques, namely, diffusion tensor imaging (DTI) and the triple stimulation technique (TST). RESULTS MEP gain revealed a significant difference between the patients and healthy control subjects in contrast to MEP area and MEP/CMAP area ratio. The diagnostic utility of MEP gain was comparable with that of TST and superior to that of DTI. CONCLUSION MEP gain can distinguish ALS patients from control subjects and may be helpful for the diagnosis of ALS. SIGNIFICANCE MEP gain appears to be a useful adjunct test and noninvasive method for the assessment of corticospinal dysfunction.

Guillain-BarrÉ syndrome subtype diagnosis: A prospective multicentric European study: GBS Subtype Diagnosis

Introduction: There is uncertainty as to whether the Guillain‐Barré syndrome (GBS) subtypes, acute inflammatory demyelinating polyradiculoneuropathy (AIDP) and acute motor axonal neuropathy (AMAN), can be diagnosed electrophysiologically. Methods: We prospectively included 58 GBS patients. Electrodiagnostic testing (EDX) was performed at means of 5 and 33 days after disease onset. Two traditional and one recent criteria sets were used to classify studies as demyelinating or axonal. Results were correlated with anti‐ganglioside antibodies and reversible conduction failure (RCF). Results: No classification shifts were observed, but more patients were classified as axonal with recent criteria. RCF and anti‐ganglioside antibodies were present in both subtypes, more frequently in the axonal subtype. Discussion: Serial EDX has no effect on GBS subtype proportions. The absence of exclusive correlation with RCF and anti‐ganglioside antibodies may challenge the concept of demyelinating and axonal GBS subtypes based upon electrophysiological criteria. Frequent RCF indicates that nodal/paranodal alterations may represent the main pathophysiology. Muscle Nerve 58: 23–28, 2018.